Brown
estimates that UB313 is somewhere between 2390 and 3550
km in diameter. This would make it approximately one and
a half times the size of Pluto. Since the reflectance
of the planet (percent of light it reflects) is not
yet determined, it is not yet possible to measure its
size exactly. However, even is the planet was found to
have 100% reflectance, it would still be larger than pluto.
Hence the team is confident the object is a planet.

How
far away is the planet?

The
object currently lies nine billion miles from earth. Currently
the object is approximately 97 astronomical units from the
sun (about 97 times further from the sun than Earth is).

Where
can it be seen?

UB313
is currently almost directly overhead in the early-morning
eastern sky, in the Cetus constellation. It will be visible
over the next 6 months using high-powered telescopes.

What
is the composition of this object?

The
celestial body appears to be covered in methane ice.

What
will be the new name?

The
discoverers have submitted a proposal to the International
Astronomical Union. Speculators have promoted the planet
as "Xena" and "Lila." Xena was used
as a nickname by the discoverers, and Lila is Mike Brown's
babl daughter's name. However, Mike states that he cannot
reveal the proposed name. Unfortunately, the seemingly logical
choice of "Persephone" (wife of pluto who was
kidnapped) has already been given to an asteroid.

Why
has it not been discovered until now?

The
10th planet's orbit is at a 45-degree angle to the rest
of the solar system, in what is known as the Kuiper Belt.
Hence, it was in a location where very few would search
for a planet. According to Brown, news of the discovery
was announced earlier than expected after hackers broke
into his website and stole news of it. The team had planned
to keep the news secret until their research was completed.